Device for the control of at least one gas exchange valve

ABSTRACT

A device is indicated for controlling at least one gas exchange valve ( 10 ) for an combustion cylinder of an internal combustion engine, having an hydraulic actuator ( 12 ) for valve actuation and having a high-pressure pump that supplies the actuator ( 12 ) with a pressure medium. In order to reduce the production costs, the high-pressure pump is formed as a control-sleeve pump ( 13 ) having a stroke-driven pump plunger ( 22 ) that limits a pump chamber ( 24 ), and having a spool valve ( 13 ) surrounding this plunger. In the pump plunger ( 22 ) and spool valve ( 13 ), on the one hand a control groove ( 27 ) that runs obliquely to the stroke direction is provided, and on the other hand a spill opening ( 30 ) that cooperates therewith is provided, which together bring about a relief of pressure of the pump chamber ( 24 ) when they overlap. For the controlling of the phase position and duration of the valve actuation, the pump plunger ( 22 ) and the spool valve ( 13 ) are able to be rotated relative to one another, and the spool valve ( 13 ) is able to be displaced relative to the pump plunger ( 22 ) (FIG.  1 ).

BACKGROUND INFORMATION

[0001] The present invention is based on a device for controlling atleast one gas exchange valve that is allocated to a combustion cylinderof an internal combustion engine, as recited in the preamble of Claim 1.

[0002] A known device of this type (DE 198 26 047 A1) has, as anactuator or valve positioner, a double-acting hydraulic working cylinderin which a control piston is guided so as to be axially displaceable,this control piston being fixedly connected with the valve shaft of thegas exchange valve integrated in the combustion cylinder, or itselfforming the end thereof further away from the valve closing element. Inthe working cylinder, the control piston limits, with its two endsurfaces facing away from one another, an upper and lower workingchamber. While the lower working chamber, via which a pistondisplacement in the direction of valve closing is effected, isconstantly charged with a medium under high pressure, for examplehydraulic oil, the upper working chamber, via which a pistondisplacement in the direction of valve opening is effected, ispurposively charged with pressure medium that is under high pressure, oris again relieved of stress to approximately ambient pressure, with theaid of electric control valves, preferably 2/2-way magnetic valves. Thepressure medium under high pressure is supplied by a high-pressure pump.Of the control valves, a first control valve connects the first workingchamber with the high-pressure pump, and a second control valve connectsthe upper working chamber with a relief line that debouches into apressure medium reservoir. In the closed state of the gas exchangevalve, the upper working chamber is separated from the closed firstcontrol valve by the high-pressure pump, and is connected with therelief line via the opened second control valve, so that the controlpiston is guided into its closed position by the pressure of the mediumprevailing in the lower working chamber. For the opening of the gasexchange valve, the control valves are switched over, through which theupper working chamber is closed off from the relief line and isconnected to the high-pressure pump. Because the piston area of thecontrol piston in the upper working chamber is larger than the effectivesurface of the control piston in the lower working chamber, the controlpiston is displaced so as to open the gas exchange valve. The magnitudeof the opening stroke depends on the design of the electrical controlsignal applied to the first control valve, and the speed of openingdepends on the high pressure of the pressure medium, applied by thehigh-pressure pump.

[0003] From DE 30 14 028 A1, a fuel injection pump for internalcombustion engines is known that has a pumping and distribution plungerthat simultaneously executes a back-and-forth stroke motion and arotational motion. The pumping and distribution plunger, formed as astepped piston, limits a pump chamber. In the jacket surface of thepumping and distribution plunger, there is situated a distributionlongitudinal groove that is connected with the pump chamber and that,during rotation, successively activates pressure passages that lead topressure lines that are connected with the internal combustion engine.The number of pressure passages corresponds to the number of combustioncylinders in the internal combustion engine that are to be supplied.During the rotation of the pumping and distribution plunger, thepressure passages that are not under high pressure are successivelyrelieved of pressure, to a suction chamber, via one or more longitudinalgrooves, an annular groove, and a relief bore. The regulation of theinjected fuel quantity takes place via a spool valve that is situated onthe pumping and distribution plunger in axially displaceable fashion andcan be axially displaced by an hydraulic controller. The pumping chamberis connected, via bored holes in the pumping and distribution plunger,with longitudinal grooves situated on the jacket surface thereof thatwork together with an opening in the spool valve. As long as these boredholes are controlled to open by the molded opening via the longitudinalgrooves, no injection takes place. However, as soon as these boredopenings are blocked, and simultaneously, during the pressure stroke ofthe pumping and distribution plunger, the distribution longitudinalgroove coincides with one of the pressure passages, injection takesplace. The injected quantity is thus determined by the spacing of thelongitudinal grooves, at least one of the longitudinal grooves beingsituated obliquely to the other, so that an axial displacement of thespool valve causes an alteration of the activation distance, and thus ofthe injected quantity.

[0004] Through further rotation of the spool valve, the beginning andend of the injection are simultaneously displaced.

[0005] What is known as a control-sleeve in-line fuel-injection pump isknown for diesel engines (Bosch, “Automotive Handbook”, 23rd ed., ISBN3-528-03876-4, pp. 542 and 543), having, for each combustion cylinder ofthe diesel engine, a pump plunger that limits a pump chamber and isdriven by a cam and that has an oblique control groove that is connectedwith the pump working chamber, and what is known as a control sleevethat is provided with a spill port. A setting shaft having a pluralityof control-sleeve levers, of which each engages in a respective controlsleeve, moves all the control sleeves in common. An electromagneticactuator mechanism in turn rotates the setting shaft. According to theposition of the control sleeve, the delivery begins earlier or laterrelative to the actuating cam. The delivery end is achieved when thecontrol groove and the spill port coincide.

ADVANTAGES OF THE INVENTION

[0006] The device according to the present invention for controlling atleast one gas exchange valve allocated to a combustion cylinder of aninternal combustion engine, having the features of Claim 1, has theadvantage that through the combination of the production of pressure onthe one hand and the controlling of the opening stroke and of the timeof opening of the gas exchange valve in the control-sleeve pump on theother hand, the outlay of control valves and control electronics, aswell as functional software, is reduced. The control-sleeve pump used isa mature component that has proven its effectiveness in fuel-injectionsystems for internal combustion engines, e.g. as an element of thecontrol-sleeve in-line fuel-injection pump described above, and thus haslow susceptibility to failure. Its installation is simple. Through thesavings of electrical control valves, the electronic outlay in thecontrol apparatus is also reduced, and the energy consumption islowered. Given a plurality of gas exchange valves in the internalcombustion engine, each having an associated control device, both theload control and the phase displacement of all the gas exchange valvescan be carried out through identical rotation of the pump plungers, oridentical axial displacement of the spool valves of all the controldevices. A switching off of the valves or of the cylinders of theinternal combustion engine can be realized using additional simpleelectrical control valves having a low switching time requirement.

[0007] Advantageous developments and improvements of the deviceindicated in Claim 1 are possible through the measures stated in theadditional claims.

[0008] According to a preferred specific embodiment of the presentinvention, the control groove is incorporated into the jacket of thepump plunger, and is connected with the pump chamber via a connectingbore that runs in the pump plunger, while the spill opening in the spoolvalve is realized in the form of a radial bore. Through axialdisplacement of the spool valve, the phase position of the opening ofthe gas exchange valve, i.e., the time of opening relative to that ofthe other gas exchange valves, is adjusted, and through rotation of thepump plunger the duration of the opening of the gas exchange valve isadjusted.

[0009] According to an advantageous specific embodiment of the presentinvention, a non-return valve is situated between the pump chamber andthe pump outlet, and a relief opening that can optionally be shut offusing an electrically controllable shutoff valve is connected to thepump outlet. The shutoff valve is preferably formed as a 2/2-waymagnetic valve having a spring return mechanism. In this way, theopening of the gas exchange valve can be executed with a variablestroke, the non-return valve connected before the pump outlet preventingan immediate intake of the gas exchange valve at the spill of thecontrol-sleeve pump, so that the instantaneous stroke of the gasexchange valve is maintained. The opening of the shutoff valve at thecorrect time triggers the closing process of the gas exchange valve bythe valve closing spring. Through these measures, a fully variable valvegear is achieved, with which, given a small load of the gas exchangevalve, opening takes place only for an extremely short time, in order toadmit only a very small quantity of fresh gas into the combustioncylinder, in order to lower fuel consumption. Such an extremely shortopening of the gas exchange valve is possible only through asuperproportional reduction of the valve stroke. Through the constantholding open of the shutoff valve, the gas exchange valve can be keptconstantly closed, and a valve or cylinder shutting off can be realizedin the internal combustion engine.

[0010] If variable stroke control is omitted, in a simplified embodimentof the control device according to the present invention, instead of thenon-return valve and electrically controlled shutoff valve a simplepressure limiter or overflow valve, which opens mechanically when thereis excess pressure, can be connected to the pump outlet of thecontrol-sleeve pump. This simplified and more economical version of thecontrol device can advantageously be used for the controlling of thedischarge valves, because here a variable opening stroke is of noparticular interest.

[0011] According to an advantageous specific embodiment of the presentinvention, given a plurality of gas exchange valves to each of which anactuator is allocated for valve actuation, the actuators for selectedgas exchange valves situated in different combustion cylinders can beconnected to a common control-sleeve pump, resulting in an additionalsavings of cost. Here, for each two actuators a switchover valve isprovided, such that one actuator is connected to each of the two valveoutlets thereof, and the valve input thereof, which can optionally beconnected with the valve outlets, is adjacent to the pump outlet of thecontrol-sleeve pump. The switchover valve is preferably fashioned as a3/2-way magnetic valve having a spring return mechanism.

DRAWING

[0012] The present invention is described in more detail in thefollowing on the basis of exemplary embodiments presented in thedrawing. The figures show:

[0013]FIG. 1 a diagram of a device for controlling a gas exchange valve,

[0014]FIG. 2 an enlarged sectional view of a control-sleeve pump in thecontrol device according to FIG. 1,

[0015]FIG. 3 in the same representation as in FIG. 1, a simplifiedversion of the control device,

[0016]FIG. 4 a diagram of the control device for controlling gasexchange valves allocated to two different combustion cylinders.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0017] The device shown in the diagram in FIG. 1 for controlling a gasexchange valve 10 for a combustion cylinder—shown partially with itscylinder head 11—of an internal combustion engine in motor vehicles hasan hydraulic actuator 12 for valve actuation and a high-pressure pump,formed as a control-sleeve pump 13, that charges actuator 12 with amedium under high pressure, e.g. hydraulic oil.

[0018] Gas exchange valve 10, situated in cylinder head 11 of thecombustion cylinder, can be an intake valve or an outlet valve. It has,in a known manner, a valve element 15 that closes a valve opening 14 andthat formed on a valve shaft 16 and cooperates with a valve seat 17surrounding valve opening 14.

[0019] Actuator 12 has a control piston 19 that is guided indisplaceable fashion in a working cylinder 18, and that limits anhydraulic working chamber 20 and is coupled with valve shaft 16 of gasexchange valve 10, and is fashioned in one piece with this shaft in theexemplary embodiment. In order to open gas exchange valve 10, controlpiston 19 is displaced against the force of a valve closing spring 21 bymedium that is under high pressure and that is introduced into hydraulicworking chamber 20 by control-sleeve pump 13.

[0020] Control-sleeve pump 13 has a pump plunger 22 that limits, in apump cylinder 23, a pump chamber 24, and is driven to execute a strokemotion by a cam 26 that is situated in rotationally rigid fashion on acamshaft 25, when camshaft 25 rotates. As can be seen more clearly inthe enlarged view of control-sleeve pump 13 in FIG. 2, in the jacket ofpump plunger 22 there is incorporated a control groove 27 that runsobliquely to the stroke direction of pump plunger 22, i.e., at an acuteangle to the pump plunger axis, and that is connected with pump chamber24 via a blind bored hole 28 situated axially in pump plunger 22, in aconnection that permits the exchange of pressure medium. Control-sleevepump 13 additionally has a spool valve 29 that surrounds pump plunger22. In spool valve 29, a spill opening 30 is made in the form of aradial bore, shown in FIG. 2 in broken lines, because in the sectionalrepresentation it is situated in the cut-away half of annular spoolvalve 29. If, during the stroke of pump plunger 22, control groove 27and spill opening 30 overlap, pressure medium can flow out of pumpchamber 24, which relieves pump chamber 24 of pressure. As is indicatedsymbolically by arrow 33, spool valve 29 can be displaced axially onpump plunger 22, for which purpose an actuating lever 31 of a controllerengages in a guide groove 32 on the outer periphery of spool valve 29.As is indicated by arrow 34 in FIG. 2, pump plunger 20 is fashioned soas to be able to be rotated about its axis. For the rotation of pumpplunger 22, an actuating element (not shown) engages thereon. Throughthis rotational adjustment of pump plunger 22, the duration of openingof gas exchange valve 10 is altered, while through displacement of spoolvalve 29 it is possible to influence the phase position of the openingof gas exchange valve 10, i.e., the time at which gas exchange valve 10is opened relative to a reference time.

[0021] Pump chamber 24 is connected with a pump inlet 36 via a pumpinlet valve 35, formed as a non-return valve, and is connected with apump outlet 38 via a non-return valve 37 whose blocking direction isoriented towards pump chamber 24. Pump inlet 36 is connected to apressure medium reservoir 39, and pump outlet 38 is connected tohydraulic working chamber 20 of actuator 12.

[0022] For the controlling of a variable stroke of gas exchange valve 10for the purpose of achieving an extremely short opening duration of thegas exchange valve in partial load and low load operation of theinternal combustion engine, there is connected to pump outlet 38 anadditional relief opening that can be optionally closed by anelectrically controllable closing valve 40. In the exemplary embodimentshown in FIG. 1, the relief opening is connected with a return line 41that leads to pressure medium reservoir 39, and a 2/2-way magnetic valve42 having a spring return mechanism is used as shutoff valve 40. Thismagnetic valve 42 is for example formed so as to be open withoutcurrent, and, for an opening stroke of gas exchange valve 10 that is tobe introduced, is led into its closed position by a control device (notshown), by being supplied with current. If, during the activationprocess of gas exchange valve 10, the current to magnetic valve 42 isswitched off, magnetic valve 42 opens, and triggers, through the reliefof hydraulic working chamber 20, the closing process of gas exchangevalve 10 by valve closing spring 21.

[0023] The operation of the control device is as follows:

[0024] Upon rotation of camshaft 25, pump plunger 22 is driven by cam 26to execute a continuous back-and-forth stroke motion, such that whenthere is a downward-directed stroke motion pump chamber 24 is filledwith pressure medium from pressure medium reservoir 39 via pump inlet 36and pump inlet valve 35. During the upward-directed stroke motion, assoon as lower edge 291 of spool valve 29 closes the lower edge ofcontrol groove 27, called control edge 271, pressure builds up in pumpchamber 24. Via pump outlet 38, this pressure is introduced intohydraulic working chamber 20 of actuator 12, through which controlpiston 19 is displaced against the spring force of valve closing spring21, and gas exchange valve 10 is opened. If spill opening 30 made inspool valve 29 overlaps with control edge 271, this pressure isrelieved, through which the spill of control-sleeve pump 13 is achieved.After the spill, non-return valve 37 prevents the immediate intake ofgas exchange valve 10, so that the instantaneous valve stroke ismaintained. If now, or at an earlier time, i.e. already during thedelivery stroke of control-sleeve pump 13, the current is shut off tomagnetic valve 42, which is closed when supplied with current, then atthe desired time return line 41 to pressure medium 39 reservoir opens,which triggers an immediate closing of gas exchange valve 10 by valveclosing spring 21.

[0025] The control device shown in a block diagram in FIG. 3 is modifiedin relation to the control device described by FIG. 1 in that thenon-return valve between pump chamber 24 and pump outlet 38 has beenomitted, and return line 41 to pressure medium reservoir 39 is connectedto pump outlet 38 not via an electrically controllable shutoff valve,but rather via a simple pressure limiter or overflow valve 43, whichopens mechanically when there is excess pressure. In this case, incontrast to the case shown in FIG. 1 with magnetic valve 42, a variablestroke cannot be controlled, but the opening and closing time, i.e. theduration and phase position of the opening of gas exchange valve 10,can, as described, be varied via the axial displacement of spool valve29 and the rotation of pump plunger 22. In other respects, the exemplaryembodiment according to FIG. 3 corresponds to the exemplary embodimentaccording to FIG. 1, so that identical components have been providedwith identical reference characters.

[0026] In the case of gas exchange valves 10, an actuator 12 isallocated to each gas exchange valve 10, and actuators 12 can beconnected to a common control-sleeve pump 13 by selected gas exchangevalves 10 situated in various combustion cylinders 11. A precondition ofthis is that the opening times of the various gas exchange valves 10 donot overlap.

[0027] As is shown in the exemplary embodiment according to FIG. 4 ofthe control device for two gas exchange valves 10 situated in differentcombustion cylinders, an actuator 12 is allocated to each gas exchangevalve 10, and in addition a switchover valve 44 is provided that has twovalve outlets 442, 443 and has a valve inlet 441 that can optionally beconnected with valve outlets 442, 443. In the exemplary embodiment shownin FIG. 4, switchover valve 44 is formed as a 3/2-way magnetic valve 45having a spring return mechanism. An hydraulic working chamber 20 of anactuator 12 is connected with a respective valve output 442 or 443,while valve inlet 441 is adjacent to pump outlet 38. In therepresentation shown in FIG. 4, the upward motion of pump plunger 22 ofcontrol-sleeve pump 13 in its pump chamber 24 results in the buildup ofa high pressure that has been introduced into hydraulic working chamber20 of actuator 12 (shown at the left in FIG. 4) due to the switchingposition of switchover valve 44, and has resulted in an opening motionof valve element 10. Hydraulic working chamber 20 of actuator 12 (shownat right in FIG. 4) is shut off by switchover valve 44 and is withoutpressure, so that gas exchange valve 10 (at the right in FIG. 4) is inits closed position. For the controlling of gas exchange valve 10 (atthe right in FIG. 4), switchover valve 44 is to be switched over, whichrepresents only a small demand in terms of switching time. In otherrespects, the design and manner of operation of the control deviceaccording to FIG. 4 correspond to those shown in FIG. 1, so thatidentical components have been provided with identical referencecharacters.

[0028] The invention is not limited to the exemplary embodimentdescribed above. Thus, the rotational movability of pump plunger 22 canbe omitted, and instead spool valve 29 can have, in addition to itscapacity for axial displacement, a rotational controlling. The situationof control groove 27 and spill opening 30 in pump plunger 22 and spoolvalve 29 can be exchanged.

What is claimed is:
 1. A device for controlling at least one gasexchange valve (10) allocated to a combustion cylinder of an internalcombustion engine, having an hydraulic actuator (12) for valve actuationand a high-pressure pump that charges the actuator (12) with a pressuremedium under high pressure, wherein the high-pressure pump is formed asa control-sleeve pump (13) having a pump plunger (22) that executes astroke motion and that limits a pump chamber (24), and having a spoolvalve (29) that surrounds the pump plunger (22), of which one has acontrol groove (27) that runs obliquely to the stroke direction of thepump plunger (22) and the other has a spill opening (30) that workstogether therewith, which when overlapping effect a relief of pressureof the pump chamber (24), and the pump plunger (22) and the spool valve(29) are able to be rotated relative to one another, and the spool valve(29) is able to be displaced relative to the pump plunger (22), for thecontrolling of the phase position and the duration of the activation ofthe gas exchange valve (10) through the activation. and deactivation ofthe actuator (12).
 2. The device as recited in claim 1, wherein thecontrol groove (27) is incorporated in the jacket of the pump plunger(22), and is connected with the pump chamber (24) via a connecting bore(28) that runs in the pump plunger (22), and the spill opening (30) issituated in the spool valve (29) and is formed as a radial bore.
 3. Thedevice as recited in claim 1 or 2, wherein the pump chamber (24) has apump inlet (36) connected to a pressure medium reservoir (39) and has apump outlet (38) connected with the actuator (12), and a pump inletvalve (35) is situated between the pump chamber (24) and the pump inlet(36).
 4. The device as recited in claim 3, wherein the pump inlet valve(35) is a non-return valve.
 5. The device as recited in claim 3 or 4,wherein the actuator (12) has a control piston (19) that is coupled withthe gas exchange valve (10) and that limits an hydraulic working chamber(20) and is able to be displaced against a valve closing spring (21) bypressure medium introduced into the working chamber (20), and thehydraulic working chamber (20) is connected to the pump outlet (38) ofthe control-sleeve pump (13).
 6. The device as recited in one of claims1 through 5, wherein the pump plunger (22) is driven to execute a strokemotion via a cam (26) situated on a camshaft (25).
 7. The device asrecited in one of claims 1 through 6, wherein a pressure limiting valve(43) is connected to the pump outlet (38).
 8. The device as recited inone of claims 1 through 6, wherein a non-return valve (37) is situatedbetween the pump chamber (24) and the pump outlet (38), and a reliefopening that is able to be closed optionally by an electricallycontrollable shutoff valve (40) is connected to the pump outlet (38). 9.The device as recited in claim 8, wherein the shutoff valve (40) is a2/2-way magnetic valve (42) having a spring return mechanism.
 10. Thedevice as recited in claim 8 or 9, wherein a return line (41) that leadsto the pressure medium reservoir (39) is connected to the reliefopening.
 11. The device as recited in one of claims 1 through 10,wherein, given a plurality of gas exchange valves (10), an actuator (12)is allocated to each gas exchange valve (10), and the actuators (12) ofgas exchange valves (10) allocated to selected different combustioncylinders are connected to a common control-sleeve pump (13).
 12. Thedevice as recited in claim 11, characterized in that the connection iscarried out using a switchover valve (44) having a valve inlet (441)that is able to be connected optionally with two valve outlets (442,443), and one actuator (12) is connected with each valve outlet (442,443) of the switchover valve (44), and the valve inlet (441) of theswitchover valve (44) is adjacent to the pump outlet (38).
 13. Thedevice as recited in claim 12, wherein the switchover valve (44) is a3/2-way magnetic valve (45) having a spring return mechanism.
 14. Thedevice as recited in one of claims 1 through 13, wherein the pumpplunger (22) of the control-sleeve pump (13) is formed so as to becapable of rotation.